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采用拉伸试验机、金相显微镜、XRD、SEM以及EMPA等手段对合金元素总含量超过15%(质量分数,下同)的新型超高强Al-11.7Zn-2.2Mg-2.0Cu-0.12Zr铝合金不同固溶温度处理后的组织与性能变化规律进行了研究。结果表明:晶内的固溶度随温度升高逐渐增加,在474℃时基本达到稳定状态,约有99%的Zn、Mg以及75%的Cu溶入晶内,其余的合金元素富集在晶界第二相内,此时,第二相主要由含Cu的η以及T相构成;合金的最佳固溶温度为474℃,此时合金的抗拉强度(σb)为688 MPa、延伸率(δ)为8%;温度为476℃时,合金局部区域出现轻微过烧,导致延伸率迅速降低;断口分析显示,随固溶温度的提高,再结晶程度增加,晶界第二相数量减少,合金的拉伸断口由较低温度时的沿晶+穿晶混合断口转变为较高温度时的沿晶断口为主。
A new type of ultra-high strength Al-11.7Zn-2.2Mg-2.0Cu-0.12Zr aluminum alloy with total content of alloying elements exceeding 15% (mass fraction, the same below) was prepared by tensile testing machine, metallographic microscope, XRD, SEM and EMPA. The variation of the microstructure and properties of the alloys after different solution treatment temperatures were studied. The results show that the intragranular solid solubility gradually increases with increasing temperature and reaches a steady state at 474 ℃. About 99% of Zn, Mg and 75% Cu dissolve into the crystal. The rest of the alloying elements are enriched in The second phase mainly consists of η and T phase containing Cu; the optimum solution temperature of the alloy is 474 ℃, the tensile strength (σb) of the alloy is 688 MPa, the elongation The rate (δ) is 8%. When the temperature is 476 ℃, slight over-burning occurs in the local area of the alloy, resulting in the rapid decrease of the elongation. Fracture analysis shows that the recrystallization degree increases with the increase of solution temperature, Reduce, tensile fracture of the alloy by the lower temperature of the intergranular + transcrystalline hybrid fracture transition to a higher temperature along the intergranular fracture.